Windows Update actually requires the following services running in order to function properly (verified on Windows 8.1):

Background Intelligent Transfer Service

Network List Service

Network Location Awareness

WinHTTP Web Proxy Auto-Discovery Service

Windows Update

BTW: “Network List Service” and “WinHTTP Web Proxy Auto-Discovery Service” both have a dependency on “DHCP Client”, which is ridiculous in my opinion (bad design).
Such services should not depend on “DHCP Client”, as many machines only have static IPs and do not utilize DHCP at all.